The analysis on solid cylindrical heat source model of foundation pile ground heat exchangers with groundwater flow

• Present the significance of foundation pile ground heat exchangers (GHEs) with spiral tube.
• We obtain the analytical solutions on solid cylindrical heat source models with groundwater flow.
• Make a deep analysis on temperature response of the combined models.
• Compare the differences between pure conduction case and combined case.
• Point out the investigative importance of groundwater flow.

This paper presents a solid cylindrical simulation model of heat transfer around foundation pile ground heat exchangers with groundwater flow for ground-coupled heat pump (GCHP) applications. The analytical solutions of the temperature response in the heat transfer process including heat conduction and convection were obtained. The impact of groundwater flow on the heat transfer has been investigated. The heat transfer processes with and without groundwater flow were compared. It was found that groundwater flow has a considerable effect on the heat transfer process, especially when the groundwater flow velocity attains a certain order of magnitude. If the system is designed reasonably and groundwater temperature is below a certain range, groundwater flow is favorable to the heat transfer between the foundation pile ground heat exchangers (GHEs) and surrounding ground medium, and can improve the energy performance of the heating and cooling system of the ground-coupled heat pump for energy conservation of buildings.